About this Author

College chemistry, 1983

The 2002 Model

After 10 years of blogging. . .

Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases.
To contact Derek email him directly: derekb.lowe@gmail.com
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March 10, 2010

How Not to Do It: Liquid Oxygen Cylinders

Posted by Derek

We haven't had a How Not to Do It around here in a while, so here's a companion piece to the famous Sealed-Up Liquid Nitrogen Tank. This incident happened (as far as I can tell) about ten years ago. It's been used in a number of safety presentations then, thanks to the Airgas Corp., whose safety officer assembled a number of photos (and this is the time to emphasize that they had nothing to do with the accident itself, because people who work for a pressurized-gas company actually know how to handle pressure vessels.

As opposed to the two guys who scavenged a liquid oxygen Dewar from a scrap metal yard and decided to put it back into service. According to the most detailed report, they tried to rig up a connection to refill the cylinder, but found that it vented immediately through the pressure-relief valve. So. . .well, yeah, you know what's coming next: they took the darn thing off and plugged it shut. No more pesky venting! They filled up their cylinder, which was loaded on the back of their pickup truck, and went rolling down the interstate at lunchtime. Whereupon they had a flat tire, and pulled over for a while to fix things. . .
OK, you can look out from behind your hands now. Although I can't imagine how, neither of these two cowboys managed to get themselves killed, nor did they take out anyone else, through what appears to be sheer blind luck. According to the report, one member of the Cylinder Kings ended up being blown across five lanes of traffic, while his partner was launched forty feet in another direction. You can see from the photo how the truck weathered things. I can't imagine that a pressure wave of straight oxygen hitting tank of gasoline can end well; it's a perfectly reasonable mixture to put a payload into low-earth orbit.

Which is a good note on which to take inventory here. We have the owners of the oxygen cylinder accounted for, and their truck. What about the cylinder itself? Well, similar to the nitrogen tank referenced above, it had failed at the bottom weld and thus departed the scene of the accident like an artillery shell. It re-entered the affairs of the world a quarter of a mile away, plunging through the roof of an apartment, completely trashing the place (and severing a natural gas line in the process). As I said, how a dozen people didn't end up killed by all this is a complete mystery to me. (The red circle in that photo is where the pressure-relief device used to be. )
So the moral of this story is, I suppose, that Pressure Relief Devices Are There For A Reason. Or maybe it's "don't scrounge gas cylinders from the scrap yard and try to get them to work". Or perhaps "just because you haven't seen a pressure vessel explode yet, it doesn't mean that they can't". Or "Gegen der Dummheit kämpfen Götter selbst vergebens." Or something.

Certainly nothing like this, but I once had the pressure release on a scuba tank go shortly after having it filled at a local shop. I was 16 at the time, driving on learners permit, had put the tank in the trunk and had just pulled onto the highway when the release let go and emptied the tank very very quickly.

Everything performed as it should have, and there were no problems, but needless to say I don't have those underwear anymore. So much respect for anything under pressure, whether inert or as scary as O2.

Haha #2. I had the same thing happen with a small CO2 tank (paintball) in the back seat of a car I was driving. Not quite the same pressure level as a scuba tank, but sufficiently loud to necessitate an underwear change for me as well.

When I was much younger I was at a welding shop and witnessed the result of someone handrolling a compressed gas cylinder without the cap. They broke the valve off and like the missile the cylinder went through a 12 inch block wall and embedded itself fully inside the cab of a pickup. Quite a sight and noise. No one was injured but the truck was totaled. Needless to say that made quite and impression and later when I became a lab manager I would go "ballistic" whenever I found an unrestrained cylinder or someone moving them without the cap.

The firemen would not enter the lab because there was a hydrogen cylinder in there and instead fought the fire through the window. Everyone was evacuated to a very safe distance and from some adjacent buildings.

After the fire was out and things had cooled down, the inspectors entered the lab to find the hydrogen cylinder intact - it had been saved by the fire melting the lead that welded the waterpipes in the roof and water had run onto the cylinder continuously - keeping it cool.

The likely reason why the Dewar was in junkyard was that the jacket could not hold vacuum. Their Dewar had no real insulation so it blew up promptly on the way back. A good Dewar that is welded shut usually blows up only after a day or two...

Two university chemists in Prague in 70s went to Neratovice chemical plant to get some vinyl chloride - they could not buy the stuff from West. So their friends opened a valve for them and they condensed the stuff into a household-sized thin-wall steel tank that was designed for storing butane - it had no safety release valve. On the way back, driving the tiny Skoda car, the guy on the passenger seat who was holding that thing between his legs observed: "Say, this tank is getting awfully warm - did they have their vinylchloride stabilized? Oh shit,its polymerizing!" By the time he managed to roll down the window the the tank was already so hot he could not hold it in his hands so he opened the door and kicked it out and that thing blew behind them as soon as it hit the pavement. It happened as they were driving through a small town, and sure enough there was a patrol car and it was on April 30 - the day before first May. The guys spent night in jail and were investigated by State security on suspicion of throwing the bomb to disrupt the May 1 communist parade.

I had a friend who operated a welding shop decades ago. He used Oxygen cylinders in a Oxy-Acetylene torch. One day, a pair of his employees were carrying a fresh Oxygen cylinder down the concrete steps into the shop, with the safety cap removed. Yep, they dropped it, and it hit the steps just so that the valve was sheared off. It flew across the shop, through a 6 inch reinforced concrete wall, and embedded itself into the soil beyond. After that, you'd never find another Oxygen cylinder being moved without the safety cap in his shop.

Mentions of Torpedo cylinders reminds me of Stanley Pine's presentation of the after affects of 1994(?) Earthquake on the Cal State Northridge Chem department. Lots of devastation from broken glassware and chemical bottles but if correctly recall it was several decapitated cylinder events that caused most damage. One picture showed total punch through a cider-block wall, could have even been two walls, before stopping. The result was massive CAL OSHA regulations in late 90's and early 2000s to earthquake proof labs that required significant effort (and those that saw Pine's lecture had great willingness). Ironically I believe was mandatory for industry to comply but schools/academic labs were not incorporated, although institutions of learning may have been added later/since.

I *really* wish someone would show this to the cops. I'm so sick and tired of seeing welders and construction trucks driving around with their oxyacetylene or high pressure inert gas cylinders uncapped, regulators flapping in the breeze at 70+ MPH on the highways. I'm not much for traffic enforcement, but seeing that daily scares me.

I was driving down I-75 in Florida just north of Lake City about 5 years ago. A welding company truck full of cylinders blew a tire in the right lane ahead of me. The truck swerved sharply to the right, causing 7 or 8 cylinders of acetylene to go flying down the interstate. Cars and 18-wheelers were running off the road, trying to avoid the cylinders, most of which were rolling merrily down the highway. After about 30 seconds, everyone and everything had come to a stop.

At this point, not one cylinder had gone off. So these two guys from the welding company start collecting the cylinders. One of them TOSSED a cylinder into the back of the truck, and it was at that point that the valve sheered off. There was a tremendous cloud of acetylene and water vapor, and we all witnessed the tank shoot off at a 45 degree angle into the palmetto scrub. Somehow, it didn't ignite. Then the guy who tossed the tank looked at the other guy from the welding company and shrugged his shoulders as if to say "what are you looking at me for?"

it was not water vapor what you saw - it was actually acetone. As acetylene is so highly endothermic, a tank of compressed pure acetylene would be a massive explosion hazard. Acetylene for welding hence comes stabilized by addition of acetone to make it less shock sensitive.

Somewhere I read a report about a LNG plant in Mexico where repairs were underway on an empty and flushed high pressure line. Sadly, this info was wrong, and a worker cut into a 900 psi pipeline with a cutting torch.

Ouch. Massive amounts of stored potential energy demand respect whatever the form...I'm an engineer (industrial control) and a colleague of mine once witnessed a ten ton roller in a paper mill operating at a zillion revs come off its supports. It went through the factory like a battering ram, sheared straight through several 12 inch steel I-beams, crashed though a cinder block wall and demolished several cars in the carpark before finally coming to rest. Thankfully no casualties.

Something else a little more on topic but that I'm so glad I wasn't there for - commissioning of a LOX plant at a zinc and lead smelter. The smelter wasn't ready to take the LOX flow so they were venting to atmosphere during the test runs, and despite the strict rules against smoking the French engineer was apparently chaining Gauloises while watching the run. Now I'm a heavy smoker but I have some sense of self preservation! Lighting up in an oxygen rich environment is a bit too much for me.
I spent a fair bit of time at that smelter subsequently, it was a safety disaster - they had a 10k gallon tank of sulphuric acid built on a wooden scaffold, sure enough one day the supports collapsed and a tidal wave of concentrated acid swept through the place...

On the way back, driving the tiny Skoda car, the guy on the passenger seat who was holding that thing between his legs observed: "Say, this tank is getting awfully warm - did they have their vinylchloride stabilized? Oh shit,its polymerizing!"

Milkshake - now that makes me shudder - he was holding it between his legs? I have a little more respect for the boys than that...

Back in the late sixties had a friend that got a job delivering for a local welding supply in Tucson. One day a chain came loose. Bottle fell off of truck broke off safety cap and neck. Result Torpedo that went two city blocks thru a cement block wall and into a swimming pool. Pure luck no one was hurt

Yes, you can just walk into a welding shop and buy LOX. I knew a guy who had a huge Dewar he used for glass-blowing. His torch was propane and (gaseous) oxygen; the only problem with the LOX tank was that if you got too many people working too much you'd run the pressure down and you'd have to wait for more heat to leak in.

In retrospect it's a slightly alarming situation, since by far the prime market for (artistic) glassblowers is bongs and pipes for smoking marijuana, and not too surprisingly, most of the glassblowers I knew were customers as well. Generally pretty harmless, but you really do want to be thinking clearly when working with a big tank of LOX...

when working with any dewar, you must always test r/valves, there are two valves and if one fails the next one will vent (or should do)lox will start to boil and turn to vapour @ -183C. a 32L dewar will lose 5lb of gas per 24hours in room temp. when using lox treat it like a bomb??????

when working with any dewar, you must always test r/valves, there are two valves and if one fails the next one will vent (or should do)lox will start to boil and turn to vapour @ -183C. a 32L dewar will lose 5lb of gas per 24hours in room temp. when using lox treat it like a bomb??????

Hey there, I'm a glassblower, and yes, I do make pipes, bubblers, bongs, etc, and yes,I do use a HEAVY amount of cannabis on a day to day basis.... The thing to be emphasized here is that I am a PROFESSIONAL, and I (and every other glassworker I've known) have a very very healthy respect for that huge cylinder in my studio. I've spoken with many representatives from many gas companies, and ironically, Glassblowers have the LOWEST accident rate of any liquid gas users. this comes for a number of reasons, but the biggest I feel is that stoners tend to have a higher respect for life and safety than a lot of folks, especially roughnecks who use fire for a living. further, our torches are stationary, and fire codes are WAY stricter on us than other "hot" industries..... sorry to take a personal note on this one, but I think it's sad the judgement people pass on others based upon cannabis use, but take no note of the alcoholism that is rampant in welding shops, or of the heavy amount of (prescription) narcotic use in hospitals (the nations largest user of liquid oxygen)..... just my two cents....

One point to be made is that the dewar should have been made useless before disposing of it in a junk yard. Similar to removing the doors off refrigerators before putting them out on the street. It prevents children, or those with child-like minds, from playing around with them, endangering theirs and others lives. A couple of holes drilled in the side of the dewar tank would have prevented these "cowboys" from using the tank.

Some years back — in fact in another millennium and another life — I was an EMT-B called to the scene of a house fire. The fire had started, probably as a result of spontaneous combustion, in a supply cabinet filled with paints and solvents and fun stuff like that. (I picture to myself some oil-soaked rags carelessly left in a pile …)

However, it seems that there was a large oxygen cylinder in the house for some reason unknown to me. Fully charged to 2000 psi. And located just on the other side of the (drywall) wall from the source of the fire. It didn't burst, of course; once the fire started burning through the wall and the metal got warm enough, the Wood's-metal ring holding in the cap melted, creating an instant venting and propulsion of the tank into a corner of the foundation.

The upside is that the tank didn't propel itself through the outer wall and into the next house.

The downside is that it injected enormous amounts of pure oxygen into a space already undergoing vigorous combustion. The fire went from "localised" to "structure fully involved" in about forty-five seconds.

Fortunately, there were no firefighters within the house at the time; the house owner had alerted them to the presence of the oxygen cylinder and to its location.

Lesson: Oxygen is (duh!) an irrepressible oxidiser, sings songs of its heart's love and passion to any fuels that may be nearby, and if given half a chance will sweep its way to them to try to make blazing romance. All other things being equal, it should be kept cloistered away from concentrated fuel loads, especially those filled with similarly energetic desires to mate with oxygen and give birth to many moles of carbon dioxide.

Having read this I believed it was rather informative. I appreciate you spending some time and effort to put this informative article together. I once again find myself personally spending a significant amount of time both reading and posting comments. But so what, it was still worthwhile!

Hmmm... makes me look with renewed interest at the oxy-acetylene set standing in a corner of my garage. I think I might relocate them away from my cans of paint and thinners, to the opposite wall. Or relocate the paint. Not so much that I'm afraid of the cylinders themselves starting anything (they're securely clamped onto a hand trolley), as their complicating effect should a can of paint thinners catch fire in their vicinity.

Yes I had previously thought of the effect of the oxygen cylinder's contents, but Getheren just threw it into sharp focus.

Regarding the original post, and the extraordinary results on the pickup truck, I assume it wasn't just the pressure wave from the release of the oxygen, I assume it's believed that it blew the fuel tank apart and the resultant fuel-oxygen mixture exploded? It just looks like ... more ... than a blast of high-pressure gas would achieve on its own.